Distribution device

ABSTRACT

An improved foam spray nozzle adapted, in a principal embodiment, for pneumatically driving a viscous stream of urethane foam constituents onto substrates in a controlled pattern and thickness uniform coating being projected by a gas jet arrangement in a prescribed &#39;&#39;&#39;&#39;ballistic&#39;&#39;&#39;&#39; fashion whereby the jet ports surround an open-ended material outlet and are disposed and tilted in a pattern reflecting the contemplated spray pattern.

United States Patent 91 Eliason et al.

[ DISTRIBUTION DEVICE [75] Inventors: Kay E. Eliason, Fort Madison,Iowa;

James R. James, Louisville, Ky.

[73] Assignee: Atlantic Richfield Company, New

York, N.Y.

[22] Filed: Sept. 17, 1971 [21] Appl. No.: 181,440

[52] US. Cl 239/296, 239/424.5 [51] Int. Cl B051) 7/10 [58] Field ofSearch 239/290, 291, 296,

[56] References Cited UNITED STATES PATENTS 8/l949 Bell et al 239/291 x3/1903 Lassoe et a1. 239/421 X June 26, 1973 2,894,691 7/1959 Sedlacsik239/291 X 3,199,789 8/1965 James 239/549 X 3,592,391 7/1971 Bender239/424.5 X

Primary Examiner-Allen N. Knowles Assistant Examiner-Michael MarAttorney-John J. McCormack et al.

' [5 7] ABSTRACT An improved foam spray nozzle adapted, in a principalembodiment, for pneumatically driving a viscous stream of urethane foamconstituents onto substrates in a controlled pattern and thicknessuniform coating being projected by a gas jet arrangement in a prescribedballistic fashion whereby the jet ports surround an open-ended materialoutlet and are disposed and tilted in a patter reflecting thecontemplated spray pattern.

11 Claims, 8 Drawing Figures PAIENTEDmzs ma 3.741. 482

sum 10; 3

DISTRIBUTION DEVICE BACKGROUND OF THE INVENTION This invention relatesto gas driven distribution nozzles and in particular to such nozzles asadapted for applying urethane foam or related viscous coating materialsonto a substrate; and more particularly where such foam nozzles comprisea liquid delivery system including mechanical impeller means and anannular outlet slit; this delivery system being operatively coupled witha pneumatic drive system comprising jet ports surrounding the deliveredviscous material and being dimensioned, disposed and tilted to project apredetermined foam coating pattern onto a substrate very uniformly andwith little waste despite variations in significant operatingparameters.

In the prior art, workers appreciate that pneumatic (gas driven) foamdistribution devices or spray nozzles have not to date satisfactorilyhandled many of the operational problems typically confronted. One suchproblem involves the maintenance of close control over coating thicknessuniformity. Typically a considerable portion of foam material is wastedon the coated substrate while the coating pattern will vary in thicknessbeyond the desired tolerances. Of course any unnecessary thickness inthe coating and any material applied beyond the intended coating pattern(off-spray material) results in an unnecessary waste of materials anduseless costs.

Moreover, in certain cases such as the application of urethane foams itis vitally important to maintain a precise uniform coating thicknessentirely apart from waste considerations. For instance, coatingthickness may dictate and determine the position and spacing ofsuperposed layers such as overcoatings or applied structural members.More particularly, spraying a foam blend for thermal insulation andstructural purposes can typically involve coating a substrate in aprescribed pattern as thin as a few mils (e.g. 0.004 in.as liquid beforefoaming), with depth tolerances as small as 1 part in 12 (or 8 percent,here 10.0003 in.). In such situations we have found that even the bestfoam nozzles presently available have inadequate depth control; forinstance using them to produce a foam depth of approximately 1 in.minimum, thickness would typically require that one set'for a nominalthickness of about I A in. (wasting about 50 percent of the materials)supply to assure maintaining the minimum 1 in. depth everywhere acrossthe substrate. On the other hand, we have found that using the subjectinvention one can reduce such excess considerably; for instance, to aslittle as a inch excess for a nominal of l k in. coating-a mere 8percent excess! Now workers in the art are well aware that a verynon-uniform and uneven (regarding area and volume) pattern often resultsusing conventional foam nozzles. For example, the pneumaticmix nozzlewidely used to spray a desired pattern can often involve such massivegas thruput (for mixing purposes) and such sensitivity to minor changesin conditions that a substantial overspray and loss of materials to theair and outside of the desired coating pattern results-often accompaniedby unacceptable thickness variations. Mechanically mixed nozzle unitsmay be used instead; however in either case the volume applied toselected pattern area is too unpredictable and nonuniform.

The prior art has of course made available a large number of spraynozzles of various types, though relatively few are adaptable forapplying foam materials. For instance, there are spray nozzles whoseoutlet orifices are arranged to control the shape of the spray pattern.However, these, and many similar nozzles, are unfortunately overlysensitive to minor shifts in operating conditions; e.g. with the rate ofmaterial supply, or with material viscosity and/or with nozzle height orgas drive thruput, turbulence, temperature, etc.

Also, such nozzles typically cannot feed (meter) the materials directlyfrom the mixing unit to the distribution orifice but rather must channelit and thus have closed-ended metering. Further, various units such asthe aforementioned pneumatic mixing units integrate the (foamconstituent) mixing operations with the gas-driven atomizing-sprayprojecting operations, synergistically compounding the fickleness ofeach so that the resultant unit is disturbingly sensitive to operatingconditions and quite difficult to get constant stable performance from.

In contradistinction to such features as those aforementioned, thepresent invention will be seen to provide a novel foam distributionapparatus wherein the applied pattern has no necessary relation to theshape of the (liquid or gas) ports; where pattern shape and size do notvary with material viscosity or flow rate nor with the gas thruput orturbulence, nor even with noz zle height, but rather remain constantwithin wide operating limits, despite such changes; and provideapparatus wherein liquid may be fed directly from a mixing stationwithout any channeling or like constriction (i.e. open-ended metering)while yet separating the mixing function from the distribution (sprayprojection) functions.

US. Pat. No. 3,199,789 issued Aug. 10, I965, and the references recitedtherein are representative of prior art foam nozzles involving suchproblems.

Accordingly, one object of this invention is to provide a better answerto the foregoing problems and provide the features of improvementdiscussed herein. A more specific object is to provide a foam nozzleadapted to project a constant applied pattern with a high degree ofdepth uniformity. A related object is to provide the foregoing withminimal waste. A more particular object is to provide the foregoing forinternal mechanically-mixed liquid compositions. Yet a further objectisto provide the foregoing using a prescribed projected pattern of gasjets symmetrically opposed around the liquid eject means.

LIST OF FIGURES The foregoing objects and features of invention aredescribed hereinafter so as to enable those schooled in the art to makeand use the claimed invention, this description to be read inconjunction with the accompanying drawings which comprise:

FIG. 1. A bottom perspective view of an embodiment of the inventionshown in conjunction with a schematic representation of its associatedspray pattern;

FIGS. 2, and 2A. An isometric view of the principal components of amixing arrangement useful in conjunction with the embodiment of FIG. 1,the components being shown in exploded fashion; plus a sectional view ofthe impeller therein;

FIG. 3. An elevational section, somewhat simplified and enlarged, of thenozzle embodiment in FIG. 1;

FIG. 4. A bottom view of the gas drive (jet) ports of the embodiment inFIG. 1;

FIG. 5. An idealized representation of the disposition and relativeangular orientation of the jet ports indicated in FIG. 4;

FIG. 6. A bottom view of the embodiment after the manner of FIG. 4,however with the associated spray pattern projected from the jetoverlain thereon; and

FIG. 7. A sectional elevation along the lines of FIG. 3 with thatembodiment being somewhat modified, here, to reduce spray diversion.

GENERAL DESCRIPTION OF PREFERRED EMBODIMENT Referring now to FIGS. 1, 3and 4, a preferred embodiment of our invention comprising a novel foamspray nozzle arrangement 40 will now be illustrated and described asfollows. Nozzle 40 will be seen to include gas drive means (jets 1-24FIGS. 4-6) concentrically surrounding the annular foam-material deliveryorifice and upstream drive (metering means) including a rotor impeller61 arranged to help mix the viscous liquid foam constituents and thrustthem through the annular orifice or meter slit EP, and beyond down andradially out to the nozzle tip, along a bevel surface 55 as indicated bythe arrows. Impeller 61 will be seen to cooperate with the jet system toproject different circumferentially-spaced streams of material indifferent selected directions to form a prescribed overall pattern offoam spray distribution according to the invention. The foam solids willbe understood as mechanically mixed internally of the nozzle housinginto a viscous slurry by the relatively conventional mixing arrangement(see FIG. 2 described below) and driven along the inside of the nozzlehousing 41 to the nozzle tip 4l-E into operative engagement with air jetmeans surrounding the tip, to there be atomized and projected toward thecontemplated substrate in a novel ballistic manner.

As indicated more particularly in FIGS. 2 and 2A (and described below),this nozzle embodiment includes relatively conventional mechanicalmixing means adapted to mix the liquid constituents and deliver themfrom the end of nozzle barrel 41 at a prescribed flow rate and withprescribed (centrifugal and downward) driving force. The object, ofcourse, is to cast the foam material in a prescribed pattern on varioussubstrates as assisted, driven and controlled by the gas drive meansaccording to the invention. This embodiment is particularly adapted tomix and spraydeposit a plurality of mixed liquid constituents to besprayed onto a substrate (e.g. ss, FIG. 5) in the form of a layer ofpolyurethane foam having a prescribed depth kept highly uniform acrossthe coated area.

Various types of mechanical mixing means will be recognized asapplicable for this embodiment. The selected means comprises acylindrical housing 41 (see FIG. 2, 2A, as well as FIGS. 1 and 3) with amechanically-driven mixing blade, or impeller, 61 rotatably mounted inhousing 41, being affixed on the driving end of a shaft ms drivenconventionally by an electric motor or the like. Although other variousmixing and driving means may be used, they will generally function tomix one, or several constituents from supply means, here indicatedgenerally as source I-I.

Impeller 61 delivers the internally-mixed foam constituents along one ofits grooves g to a meter slitEP formed by each groove end portion withthe inner face of the impeller housing 41 spaced therefrom a prescribedgap. This gap (and the meter slit it creates) may if desired be madevariable with shims or the like. Impeller 61 comprises a right circularcylinder approximately 3 Y4 inches long, with a l k inch diameter. It isrelieved at its inject-end to include a mixing chamber 63 which iscentrally-tapped at the bottom to receive drive shaft MS removableaffixed there to impeller 61 for rotation thereof by motor means M orthe like in the 2000 to 6000 rpm range. The sides of impeller 61 arerelieved with a plurality of grooves g (e.g. 12 grooves approximatelyinch deep X k inch wide) disposed equidistant and symmetrically aboutits circumference. The transport of material from injection at mixingchamber 63 to ejection at meter slit EP is effected in a known (worm)fashion. Mixing chamber 63 is about 1 inch deep and terminates in abeveled end portion 62 dished downwardly and toward the center. Chamber63 is adapted and intended to receive the liquid components from thesupply lines indicated in FIG. 2 (to mixer H) and to facilitate themixing and agitation thereof, thereafter to eject them outwardly andcentrifugally along spiral grooves g to be driven therealong towardmeter slit EP and beyond, when impeller 61 is rotated in the indicatedsense. In this embodiment the mixing arrangement will be understood asproviding the indicated components at a prescribed pressure such thatwith the impeller rotated in a range of 2,000 to 6,000 rpm a relativelyconstant foam thruput will be provided on the order of about 5 to about40 lbs. per minute through slit EP. For this embodiment the mixedejected urethane pre-foam liquid comprises a catalystadditive mixture,plus isocyanate and polyol constituents injected by supply conduits ISand PC respectively.

The mixer barrel or housing 41 has an outer diameter of about 2 incheswith walls about one-fourth inch thick, being tapered almost to a pointat its eject tip end (where tip 41-E presents an annular flat a few milswide). The taper or beveled portion 51 along the inner end of barrel 41is about three-fourths inch long and disposed at a few degrees withrespect to nozzle center line C-L and housing sides. When impeller 61 ismounted and rotated concentrically within barrel 41, a clearance ofabout one thirty-second inch is realized with inner barrel wall makingannular exit slit EP one thirty-second inch wide between grooves. Ofcourse other clearances may be provided and a variableclearance meansmay be incorporated in the device as known in the art.

GAS DRIVE DETAILS In general it is intended that the gas drive forprojecting foam materials toward the substrate according to theinvention be circumferentially distributed in the form of jet portssymmetrically and uniformly surrounding the path of foam ejection(proceeding from slit EP along bevel 55 to flat tip 4l-E) and adapted toprovide a gas stream of sufficient thruput (pressure, flow rate) and sooriented as to project a prescribed application pattern onto a givensubstrate-doing so in a manner that provides a smooth coating of uniformthickness despite normal variations in substrate distance, materialthruput and viscosity and gas drive characteristics. Accordingly andaccording to these features, housing 41 is provided with an annular slot41-S cut into its exterior wall adjacent its delivery end and bevel 55;being about 60 to mils deep by onehalf inch high. Housing 41 issurrounded by, and attached to, an air supply ring arrangement Acomprising an annular cylinder 51 2 A: inches in diameter by aboutthree-fourths inch high and relieved inwardly across its midsection todefine a Slot A-S adapted to communicate congruently with housing slot41-8, being the same height and about 400 mils deep so that together,the slots form a plenum chamber PC about one-half inch square adapted tobe supplied with pressurized air (e.g. as indicated by air supplyconduits 31,31). Plenum PC thus comprises an annular chamber adapted todistribute the injected gas stream relatively evenly to an array of jetports j comprising ports labeled 1 through 24 in FIG. 4. These portscommunicate with plenum PC and exit at the delivery end of nozzle 40 atthe outer circumferential end thereof so as to project associated airstreams for interacting with, engaging and projecting an associatedstream of foam materials driven from an associated groove exiting atslit EP. Plenum chamber PC preferably is supplied by symmetricallyopposed supply conduits so that air pressure may be distributedrelatively evenly throughout; of course for higher air pressures andincreased gas thruput, etc. four or more (rather than two) opposedconduits may be employed.

As particularly shown in FIGS. 3 and 4, jet ports j are formed in thisembodiment by cylindrical channels drilled from the outer periphery oftip 41-E to the floor of slot 41-8 in a prescribed manner (tilt angleindicated below; thru a distance of one-half to three-fourths inch).Thus, at theouter circumference of tip 41-13 a number of exit points ofthe ports are disposed symmetrically and equidistant (here, 15 apart)along the circumferential locus of the outer diameter of housing 41,concentric with centerline C-L and equidistant from annular eject slitEP. For example, FIG. 3 shows, in section, typical ports 19 and 13indicated also in'FIG. 4 and FIG. 5.

Jet ports j are preferably all 0.042 inch in diameter, though this isreadily variable within limits as seen below, depending primarily uponthe maximum total gas flow rate desired and other factors. As willbecome more evident from thedescription of FIG. 5, ports j are,according to a feature of novelty, tilted at a prescribed degree withrespect to the nozzle centerplane, defined by the aforementioned nozzlecenterline -1. and horizontal centerline CL' (indicated in FIG. 4) insuch a manner as to project a prescribed pattern onto the contemplatedsubstrate. For example, for this embodiment it will be evident thatports j are tilted to a degree directly proportional to their distancefrom this nozzle center plane and so that their projections onto aprescribed substrate about two feet away from the nozzle tip to locate aprescribed array of index points (see FIG. 5 where points are numberedand keyed to the port numbers in FIG. 4), defining a pattern ofprescribed shape and size. Here the pattern is an ellipse with a majoraxis A-Mlabout 18 inches long, (along direction C-C) and a minor axisA-MN about 1 6 inches long, along the scan direction as indicated. Thusports 1 and 13 are not tilted at all; ports 14, 24, 2 and 12 are alltilted at 17 with respect to the reference plane, ports 3, ll, 15 and 23tilted at 15; ports 16, 22, 4 and tilted at 21; ports 17, 21, 5 and 9tilted 25 and ports l8, 19, 20, 6, 7 and 8 tilted at 28. Of course theforegoing angular orientation was chosen simply to define the indicatedelliptical pattern of index points indicated in FIG. 1 by the portsprojections on a flat substrate at a reference distance of 2 feet fromnozzle tip 41-E. It will be understood that a different pattern sizeand/or shape may be rendered in like manner by a different angularorientation of ports. For instance, it has been found that compressingthe width of the indicated minor axis A-MN to about one-half inch andscanning the nozzle perpendicular to the direction indicated in FIG. 1(that is, along direction C-C) can render a thin, beautifully-defined,uniform thickness pencil pattern along a substrate" better, even', thana single nozzle orifice or the like! Of course it is recognized that thepattern defined by the port projections as indicated in FIG. 1 is not afull-width pattern as coated, since the normal impingement of thematerial from each nozzle will result in some spray outside of thislocusthat is the effective length (lp) and width (wp) of the appliedpattern will be somewhat greater than indicated in FIG. 1. This isschematically indicated in FIG. 6 wherein the bottom of nozzle 40 isshown as superimposed over its associated pattern in this embodimentwherein the locus of index points is indicated at L-I while theeffective length and width (lp and wp) are indicated with respectthereto.

Turning now to the operation of the gas driven foam nozzle described inthis embodiment and referring especially to FIG. 3, it will be notedthat impeller 61 thrusts the viscous foam material downwardly andoutwardly across annular beveled face 51 (generally in 12,relatively-separate strings from each of the 12 spiral grooves in 61) tothe outer edge of tip 41-13 where this material is acted upon by one orseveral of the air jets j, to be projected downwardly and outwardly in aprescribed and controlled array of angles toward the substrate. Forinstance, streams projected adjacent jets 19 and 13 and there beyond areindicated schematically by the dotted line arrows in FIG. 3. It has beenobserved in practice that when this embodiment is operating optimally,diagonal streams (or strings) of material can be seen projected from thenozzle for a distance 1 to 2 inches; thereafter the pattern becomesfoggy or masked over-presumably by atomization and interparticle'actionbeing completed with the particles being carried by air jets and theforce of gravity in a ballistic projectory toward the substrate. It isfurther believed that with the material thus being imparted withsufficient momentum vector that their impact upon the substrate causes asubsequent puddling, a leveling action takes place with the jet streams(including those from successive coating passes with the nozzle) helpingto level and smooth the overall coating, and all contributing towarddeveloping a uniform thickness as well. Thus, it would be apparent thatthe ballistic effect imparted by the described nozzle jet drive systemis important for distributing the foam material on the substrate andsmoothing it. More particularly it is believed that the energy impartedby the mechanical impeller to the foam materials is important. Thiscentrifugal, downward thrust can, of course, be a function of rotorspeed and the exit velocity of the materials from gap EP, this vectorbeing resolved together with that given by the associated jet streamlater. For instance, it has been found that with the indicatedembodiment and pattern. at a material thruput of 13 lbs. per minuteconstant (ARGO-Foam 1 or 2) and a constant air jet pressure, using theforegoingembodiment rotating impeller 61 at 2,000 rpm yielded a patternabout 2 /2 inches wide by about 17 inches long. Increasing impellervelocity lengthened the pattern only in the major axis direction,however, since a speed of 2750 rpm gave a pattern length of 19 incheswhile 3700 rpm gave about 24 inch length. Substantially beyond this rpm,however, the distribution pattern seems to blow out since at 4500 rpmthe major axis lengthened to about 30 inches, while the minor axissuddenly balloons-out to about 36 inches. The foregoing indicates thatwithin moderate rpm limits, the change in impeller speed imparts morevelocity to the material at the jets along the extremities of the majoraxis A-MJ in FIG. 1 (that is at jets 17, 18, 19, 20 and 21 plus 5, 6, 7,8 and 9).

In addition, air jet thruput must be kept high enough for a giventhruput of foam solids so that the foam is properly aerated and does notchoke" the pattern. For instance, for a 24 hole nozzle the air thruputassociated with a 29 mil jet will do a good application job at lbs. perminute but will not properly apply 30 lbs. per minute unless thediameter is opened up to about 42 mils.

Referring to the spray patterns described above, it should also be bornein mind that while the typical elliptical spray pattern approximatesthat shown in FIG. 1, being somewhat larger than the ellipse traced bythe index points (see the pattern shown in plan view in FIG. 6 inassociation with nozzle 40 superposed thereover observing that theeffective pattern width wp of about 3 k inches to 4 inches and effectivelength lp of about 19 inches to 20 inches) and has an even, uniformthickness, a halo" is also developed outside this pattern, comprising anoff-spray halo", OS. This off-spray halo" (FIG. 6) surrounds theeffective uniformthickness coating pattern and comprises anoutwardlytapering annulus of waste materials. Halo OS will be understoodas about 4 inches wide surrounding the effective coating pattern andtapering from the nominal coating thickness of 1 A inches to virtuallynothing at its outer periphery, the total off-spray volume in thispenumbra comprising on the order of less than 10 percent of the totalvolume of material sprayed-a considerable saving over conventionalmethods today.

Jet port diameter appears to be one factor in this offspray phenomenon.For instance, a port diameter of about 40 mils may lay down thesatisfactory given pattern at 30 psi air pressure and operating foamthruput, whereas reducing the diameter to about 35 mils or less willrender a smaller effective pattern with a larger percentage ofoff-spray. Similarly, increasing the diameter substantially providesthat a 29 mil 24 hole head operating at 13 pounds per minute gives anincreased amount or percentage of off-spray when the thruput isincreased to 30 pounds per minute unless the diameter is opened up toabout 42 mils.

Table I below summarizes a few illustrative cases indicating how the jetport diameter/foam thruput relation affects coating quality (e.g.illustrating choking effect).

TABLE I For nozzle as in EXAMPLE I, with a 24 port, 30 psi head witheverything kept constant:

Port Diameter Foam Thruput Coverage Quality Case A 0.040 inches at 13lb./min very good, uniform Case A 0.040 inches at 30 lb./min very good,uniform Case A 0.030 inches at 30 lb./min unsatisfactory Case B 0.030inches various mixed qualit (not ood" Case C 0.030 inches various etter48 ports In summary, the results achieved with the foregoing embodimenthave been quite satisfactory and a distinct improvement over present-dayalternatives. Using the aforedescribed 42 mil jets at 30 psi pressurewith the described urethane materials provided at about 13 pounds perminute thruput will be seen to yield a uniform V4 inch thick urethanefoam layer (nozzle height about 24 inches) above the substrate formingthe indicated elliptical (about 3 /2 inches X 20 inches) relatively flatlevel pattern following closely the contours of the substrate SS. Thesame resultant coating is rendered in strips of indefinite lengths bysimply scanning nozzle 40, together with associated supporting equipmentrepeatedly across the substrate to build up enough layers to develop thedesired total thickness. For instance, a number of layers like theforegoing were laid down superimposed one on the other in a sixlaminatefoam layer about 1 la inch thick by simply scanning the nozzle six timesover the same substrate strip length, allowing a few seconds curing timebetween passes. A nozzle moving at about 2 feet per second and providedon a 3 inch head stagger was found useful resulted this purpose. A veryhigh degree of thickness uniformity was achieved in that thicknessvariations of only about i /8 inch were found or 1 part in 12 (8percent). This is a signal achievement in this art as workers willattest. These laminates were laid down at a rate of 45 to 54 board feetper minute using an automatic spray machine, assuming 30 pound perminute through the nozzle which when added to the typical down time(e.g. scanning turn-arounds, etc.) )resulted in an average 18 pounds perminute effective thruput" (i.e. at the substrate).

Moreover, it was found that considerable variations in operatingconditions, such as air jet pressure (within the range of 30 to 50 psi)and foam thruput (e.g. from a few pounds up to about 25 to 30 pounds perminute) produced no significant changes in the pattern applied. Thisoperating stability and insensitivity to changes in liquid thruput andgas thruput will be recognized as significant, highly advantageous andquite unexpected by those skilled in the art.

Moreover, unlike many alternative foam distribution systems, the presentinvention is also quite tolerant of radical shifts in the viscosityand/or temperature of the foam (the latter affecting viscosity). Thatis, where alternative devices will experience a radical variation in theapplied pattern accompanying a change in viscosity and/or temperature offoam materials (e.g. especially using one of the common pneumaticmixing-projecting nozzles) the instant device is practically unaffected.As a result, the much higher viscosities as well as lower materialtemperatures may be used with the present device; much less Freon orother blowing agent is typically lost.

Of course, various changes and modifications inthe components of theforegoing embodiment may be made as contemplated by those skilled in theart to achieve the described functions and results. For instance, onemight substitute a different but equivalent mechanical mixing system, orgas jet supply system to render the same of modified pattern.Furthermore, for certain applications the relative disposition of theair jet and liquid supply systems may be shifted while still performingthe indicated functions; for instance, one may locate plenum P withinthe walls of housing 41 to emerge at some point along the length ofbeveled section 51 in FIG. 3, being angled outwardly from fromcenter-line C-L to provide the selected degrees of outward thrust.However, the same ballistic projection phenomenon will be seen to beimplemented within the spirit and scope of the subject invention.

Also, various features of the invention may be changed to produce higherand more intricate levels of sophistication. For instance, the jet portdiameters need not be kept uniform for a given nozzle design, but may bevaried to produce different coated thicknesses at different portions ofthe applied pattern. For instance, if the port diameters for nozzle 40were increased going from right to left in FIG. 1 so that the smallestand narrowest ports were located on the right (e.g. ports 5, 6, 7, 8, 9at 20 mils) with the ports getting progressively larger as one proceedsto the left so that v the largest ports are located at the leftextremity (e.g.

ports 17, 18, 19, 20, 21 at 40 mils), one might produce a pattern havinga graduated, increasing thickness in a leftward direction assuming thesame indicated scan direction and other operating conditions. (Scanningacross a stripseveral times could amplify this thickness differential.)Similarly, one might graduate the thickness in two directions, outwardfrom the center to produce a relatively U-shaped coated strip(cross-section, looking in the direction of scan). Of course, workers inthe art will visualize other applications for using suchballistic-projection foam nozzles; eg with different but related viscousi liquids materials, such as high build epoxy coatings or the like.

. Nozzle plugging is a problem endemic to all devices like thatdescribed, although the subject nozzle appears to be much'less prone,being self-cleaning and having no flow-constrictions between the mixingstation and the ejection station'(that is open-ended metering). Howeverin extreme cases if the catalyst level is so high relative to the speedof application that the material is setting up in the nozzle and beforeit has reached the substrate, a plugging problem can result, of course.(I-Iigh'temperatures like high catalyst projections can give thisproblem--too-rapid curing). In situationsv where the foam is to beapplied in a scanning operation for one or more layers, it has beenfound that, with the necessary (turn-around) down-time at the end ofeach pass, it is reasonable to equate minimum risetime with twice thisdown-time, (conversely with a 6 second rise-time, the head can never beshut-down more than about 3 seconds before plugging will begin). Here,it is also preferred to make the head and impeller components readilydemountable for cleaning and replacement.

Associated with this plugging problem is the problem of minor foambuild-up along the face of the plenum ring (see face A-F in FIG. 3). Ithas been found that material will build up on face A-F, especiallyadjacent end jets (such as 17 to 20 and 5 through 9 in FIG. I).Accordingly, and especially to minimize any such buildup problem, theembodiment modification indicated in FIG. 7 is recommended for suchsituations. Here, the air jet ring is beveled, as indicated on face51-B, away from and back from the area of nozzle tip 4l-E so as topresent a minimum overhang outwardly adjacent the exit portion of thejets (e.g. jet ports 19 and 13 in FIG. 7). Similarly, the inlet supplyconduits should be relocated back away from the face of the nozzle asindicated for conduit 31'. The embodiment in FIG. 7 also indicates(schematically) a modification whereby plenum chamber A-C isincorporated within the walls of housing 41, for instance beingfashioned as the breakaway-tip indicated as removable mounted on theforward end of barrel 41.

Although certain embodiments have been indicated by way of example andillustration, it is obvious that various modifications in the structuresand techniques shown may be made, alone or in combination, by thoseskilled in the art without departing from the spirit and scope of theinvention as defined in the appended claims. For example, equivalentelements may be substituted for parts described, parts may be reversedandlor various features used independently, while certain other featuresare eliminated; all without departing from the spirit of the invention.

What we claim is:

1. An improved nozzle device for applying coatings of controlled depthto a prescribed substrate in a predetermined pattern comprising:

Nozzle housing means including an annular tip portion; metering meanscomprising an array of annular orifices adapted to provide a prescribedsemiviscous liquid at a predetermined rate and a prescribed velocityalong selected circumferential portions of said tip portion and gasdrive means disposed to circumferentially surround said tip and adaptedto operatively engage associated portions of said liquid flow there soas to project these toward an associated part of said substrate patternin a prescribed ballistic manner.

2. The device as recited in claim 1 wherein said nozzle tip includes anannular end-flat portion; wherein gas drive means includes a source ofpressurized gas, a plenurn chamber adapted to be filled with saidpressurized gas and an array of similar gas conduits extending betweensaid plenum and an associated portion of said annular flat to present anarray of jet ports on said tip symmetrically surrounding said meteringmeans and equidistant therefrom; wherein said liquid comprises foammaterials; and wherein said metering means comprises an open-ended foamdelivery system.

3. The device as recited in claim 1 wherein mechanical mixingsimpellingmeans are provided to impart said velocity; and wherein said velocityvector together with the thrust imparted by said gas jets combine toimpart a prescribed projection energy to each associated liquid streamat said tip and thereby develop said ballistic projection.

4. The combination as recited in claim 2 wherein said gas drive means isarranged to provide a prescribed gas thruput through each jet port andwherein said metering means is adapted to supply said foam materials ata prescribed foam thruput, matched to said jet thruput, so as toaccomodate said ballistic projection and uniform coating of saidpattern, yet without producing any substantial off-spray or other waste.

5. The combination as recited in claim 4 wherein said jet ports arearranged to have a diameter less than that which produces an excessoff-spray.

6. The combination as recited in claim 4 wherein said metering means andsaid gas drive means are conjunctively arranged so that the flow ratesof gas and liquid materials are matched and wherein the means fordelivery of each are so oriented relative one another and said patternas to render an elliptical coating pattern on said substrate.

7. The combination as recited in claim 6 wherein associated nozzlemotive means are also provided in operative relation with said nozzledevice and adapted to transport said device at a prescribed rate acrosssaid substrate so as to sweep said pattern thereacross in a prescribeddirection, laying down one or more layers of said coating foammaterials.

8. The combination as recited in claim 6 wherein said liquid materialscomprise mixed foam constituents adapted to be sprayed on the substrate;wherein said gas conduit diameters are in the range of a few hundredthsof an inch; wherein said liquid material thruput is on the order of froma few to several dozen pounds per minute and wherein said gas thruputrate is equivalent to that resulting from a pressure of a few dozenpounds per square inch through gas conduits.

9. The combination as recited in claim 4 wherein said gas drive meansincludes an annular plenum ring disposed surrounding said nozzle housingadjacent said tip and attached thereto, this ring adapted to provide atleast a portion of said plenum chamber.

10. The combination as recited in claim 9 wherein said ring is taperedbackward and away from said tip in a prescribed manner adapted tominimize any foam deposition thereon.

ll. The combination as recited in claim 2 wherein said annular nozzleflat is centered on a prescribed nozzle-axis extending normal to theplane of this flat; wherein said gas drive means comprises an array ofgas conduits surrounding the outer radial circumference of said flat andequidistant from one another and from said metering means, opposed firstones of said conduits being aligned along first axes parallel to oneanother and to said nozzle axis; the rest of said conduits being tiltedat prescribed respective axes to the reference plane forward by saidaxes, each being disposed so that its projected longitudinal axisintersects a prescribed portion of said pattern on said substrate.

1. An improved nozzle device for applying coatings of controlled depthto a prescribed substrate in a predetermined pattern comprising: Nozzlehousing means including an annular tip portion; metering meanscomprising an array of annular orifices adapted to provide a prescribedsemi-viscous liquid at a predetermined rate and a prescribed velocityalong selected circumferential portions of said tip portion and gasdrive means disposed to circumferentially surround said tip and adaptedto operatively engage associated portions of said liquid flow there soas to project these toward an associated part of said substrate patternin a prescribed ballistic manner.
 2. The device as recited in claim 1wherein said nozzle tip includes an annular end-flat portion; whereingas drive means includes a source of pressurized gas, a plenum chamberadapted to be filled with said pressurized gas and an array of similargas conduits extending between said plenum and an associated portion ofsaid annular flat to present an array of jet ports on said tipsymmetrically surrounding said metering means and equidistant therefrom;wherein said liquid comprises foam materials; and wherein said meteringmeans comprises an open-ended foam delivery system.
 3. The device asrecited in claim 1 wherein mechanical mixing-impelling means areprovided to impart said velocity; and wherein said velocity vectortogether with the thrust imparted by said gas jets combine to impart aprescribed projection energy to each assOciated liquid stream at saidtip and thereby develop said ballistic projection.
 4. The combination asrecited in claim 2 wherein said gas drive means is arranged to provide aprescribed gas thruput through each jet port and wherein said meteringmeans is adapted to supply said foam materials at a prescribed foamthruput, matched to said jet thruput, so as to accomodate said ballisticprojection and uniform coating of said pattern, yet without producingany substantial off-spray or other waste.
 5. The combination as recitedin claim 4 wherein said jet ports are arranged to have a diameter lessthan that which produces an excess ''''off-spray''''.
 6. The combinationas recited in claim 4 wherein said metering means and said gas drivemeans are conjunctively arranged so that the flow rates of gas andliquid materials are matched and wherein the means for delivery of eachare so oriented relative one another and said pattern as to render anelliptical coating pattern on said substrate.
 7. The combination asrecited in claim 6 wherein associated nozzle motive means are alsoprovided in operative relation with said nozzle device and adapted totransport said device at a prescribed rate across said substrate so asto sweep said pattern thereacross in a prescribed direction, laying downone or more layers of said coating foam materials.
 8. The combination asrecited in claim 6 wherein said liquid materials comprise mixed foamconstituents adapted to be sprayed on the substrate; wherein said gasconduit diameters are in the range of a few hundredths of an inch;wherein said liquid material thruput is on the order of from a few toseveral dozen pounds per minute and wherein said gas thruput rate isequivalent to that resulting from a pressure of a few dozen pounds persquare inch through gas conduits.
 9. The combination as recited in claim4 wherein said gas drive means includes an annular plenum ring disposedsurrounding said nozzle housing adjacent said tip and attached thereto,this ring adapted to provide at least a portion of said plenum chamber.10. The combination as recited in claim 9 wherein said ring is taperedbackward and away from said tip in a prescribed manner adapted tominimize any foam deposition thereon.
 11. The combination as recited inclaim 2 wherein said annular nozzle flat is centered on a prescribednozzle-axis extending normal to the plane of this flat; wherein said gasdrive means comprises an array of gas conduits surrounding the outerradial circumference of said flat and equidistant from one another andfrom said metering means, opposed first ones of said conduits beingaligned along first axes parallel to one another and to said nozzleaxis; the rest of said conduits being tilted at prescribed respectiveaxes to the reference plane forward by said axes, each being disposed sothat its projected longitudinal axis intersects a prescribed portion ofsaid pattern on said substrate.